A first photoelectric conversion element for detecting light and converting the light into photoelectrons comprises one buried photodiode formed in a semiconductor substrate, and a plurality of MOS diodes each having an electrode formed on the semiconductor substrate with an insulator interposed therebetween. The buried photodiode has a comb shape, in which a plurality of diverging portions are disposed to diverge from one portion, when viewed from the top thereof, and the respective electrodes of the MOS diodes are disposed so as to be nested between the plurality of diverging portions of the buried photodiode when viewed from the tops thereof.